Desalination plant too expensive, NSW Opposition says

The New South Wales Coalition says a potential blow-out of the cost of the Kurnell desalination plant is further evidence it is not a viable solution to Sydney's water shortage.

The Australian Financial Review has uncovered Sydney Water documents from July last year which suggest increasing international demand for desalination equipment may inflate the cost of the plant.

The Coalition's water utilities spokesman, Andrew Stoner, says desalination should be used only as a last resort.

"You have less expensive and less environmentally damaging options like recycling, like storm water harvesting, those should be the first strategies pursued," he said.

However, NSW Premier Morris Iemma says the plant is vital to Sydney's future and the potential for costs to increase means that it should be built as soon as possible.

"If you dither and delay like Mr Debnam proposes, you'll find, if he wins the election by the time he gets around to making the decision to proceed with the desalination plant, and he will, he'll find that the cost will have escalated a lot more," he said.